12th CBSE 2026 Physics Important Questions For Exam

12th CBSE Board Gauss Paper

Chapter 1 – Electric Charges and Fields

1. State and prove Gauss’s theorem in electrostatics. (2025)

2. Derive the expression for electric field due to an infinitely long straight uniformly charged wire. (2024)

3. Derive the expression for electric field on the axial line of an electric dipole. (2023)

4. Derive the expression for electric field on the equatorial line of an electric dipole. (Probable 2026)

5. Explain why the electric field inside a conductor is zero under electrostatic conditions. (2024)

6. Define electric flux and explain its physical significance. (2023)

7. State and explain the properties of electric field lines. (Probable 2026)

8. Establish the relation between electric field intensity and force acting on a charge. (Repeated 2023-25)

Numerical Topics: Gauss theorem application, Electric field due to dipole, Dipole moment calculation

Chapter 2 – Electrostatic Potential and Capacitance

1. Derive relation between electric field and electric potential. (2025)

2. Obtain expression for electric potential due to a point charge. (2023)

3. Derive expression for energy stored in a capacitor. (2024)

4. Explain effect of dielectric on capacitance. (2025)

5. Derive expressions for capacitors in series and parallel combinations. (Repeated)

6. Derive potential energy of two charge system. (2023)

7. Explain why capacitor stores energy. (Probable 2026)

8. Define equipotential surface and explain its properties. (Probable 2026)

Numerical Topics: Equivalent capacitance network, Capacitor with dielectric slab, Energy stored in capacitor, Potential energy of charge system

Chapter 3 – Current Electricity

1. Derive relation between drift velocity and current density. (2024)

2. State Kirchhoff’s laws and apply them in circuit analysis. (2025)

3. Explain working of Wheatstone bridge and meter bridge. (2023)

4. Explain principle and advantages of potentiometer. (2025)

5. Explain temperature dependence of resistance. (2023)

6. Derive Ohm’s law. (Probable 2026)

7. EMF vs terminal voltage explanation. (Repeated)

8. Resistivity and conductivity relation. (Probable 2026)

Numerical Topics: Kirchhoff loop problems, Potentiometer EMF, Internal resistance, Wheatstone bridge resistance, Drift velocity

Chapter 4 – Moving Charges and Magnetism

1. Explain Lorentz force and its expression. (2025)

2. Radius of charged particle in magnetic field derivation. (2023)

3. State Biot-Savart law and explain. (2024)

4. Ampere circuital law & solenoid magnetic field derivation. (2025)

5. Explain Fleming left hand rule. (Probable 2026)

6. Magnetic force on current carrying conductor. (Repeated)

Numerical Topics: Circular loop magnetic field, Force on conductor

Chapter 5 – Magnetism and Matter

1. Bar magnet equivalent solenoid. (2025)

2. Magnetic dipole torque derivation. (2023)

3. Dia, Para, Ferro comparison. (2024)

4. Earth magnetism elements. (Repeated)

5. Magnetic susceptibility explanation. (2025 SQP)

6. Magnetic field lines of bar magnet. (Probable 2026)

7. Permanent vs Electromagnet comparison. (Repeated)

Numerical Topics: Magnetic dipole torque, Magnetic moment

Chapter 6 – Electromagnetic Induction

1. State and explain Faraday’s laws of electromagnetic induction. (2025)

2. Derive expression for motional EMF. (2024)

3. Explain Lenz’s law and show conservation of energy. (2023)

4. Derive expression for self inductance of solenoid. (Probable 2026)

5. Explain mutual inductance between two coils. (Repeated)

6. Explain eddy currents and their applications. (2025)

7. Explain working principle of AC generator. (Probable 2026)

8. Define magnetic flux and explain its significance. (Repeated)

Numerical Topics: Moving rod EMF, Inductance calculation, Induced current

Chapter 7 – Alternating Current

1. RMS value derivation. (2024)

2. Power factor explanation. (2025)

3. Impedance derivation in RLC circuit. (2023)

4. Resonance in RLC circuit. (2025)

5. Transformer working principle. (Probable 2026)

6. Phase relation in AC circuits. (Repeated)

7. AC power loss explanation. (Probable 2026)

8. Reactance explanation. (Repeated)

Numerical Topics: Resonant frequency & LCR Circuit, Impedance calculation, AC power

Chapter 8 – Electromagnetic Waves

1. EM wave speed derivation. (2023)

2. Transverse nature explanation. (2025)

3. EM spectrum applications. (2024)

4. Production of EM waves. (Probable 2026)

5. Properties of EM waves. (Repeated)

6. Maxwell prediction explanation. (Probable 2026)

7. Energy transport in EM waves. (Repeated)

8. Comparison with mechanical waves. (Repeated)

Numerical Topics: Wavelength-frequency relation, EM energy calculation

Chapter 9 – Ray Optics and Optical Instruments

1. Mirror formula derivation. (2025)

2. Lens maker formula derivation. (2024)

3. Total internal reflection explanation. (2023)

4. Compound microscope working. (2025)

5. Astronomical telescope working. (Repeated)

6. Refraction through prism explanation. (Probable 2026)

7. Optical fibre working. (Probable 2026)

8. Power of lens explanation. (Repeated)

Numerical Topics: Mirror formula, Lens focal length, Prism deviation, Magnification

Chapter 10 – Wave Optics

1. Young double slit experiment derivation. (2025)

2. Fringe width expression derivation. (2024)

3. Interference conditions derivation. (2023)

4. Single slit diffraction explanation. (2024)

5. Polarisation explanation. (Probable 2026)

6. Coherent sources explanation. (Repeated)

7. Thin film interference. (Probable 2026)

8. Interference vs diffraction comparison. (Repeated)

Numerical Topics: Fringe width, Path difference, Diffraction minima

Chapter 11 – Dual Nature of Matter and Radiation

1. De Broglie wavelength derivation. (2024)

2. Einstein photoelectric equation derivation. (2025)

3. Photoelectric graphs explanation. (2023)

4. Wave-particle duality explanation. (Probable 2026)

5. Threshold frequency explanation. (Repeated)

6. Stopping potential concept. (Repeated)

7. Effect of intensity and frequency. (Repeated)

8. Photon concept explanation. (Probable 2026)

Numerical Topics: Threshold frequency, Photoelectron kinetic energy, De Broglie wavelength

Chapter 12 – Atoms

1. Rutherford model limitations. (2023)

2. Bohr orbit radius derivation. (2024)

3. Electron energy derivation. (2025)

4. Explain Hydrogen spectral series. (Repeated)

5. Explain Bohr postulates. (Probable 2026)

6. Energy level diagram explanation. (Repeated)

7. Ionisation energy explanation. (Probable 2026)

8. Explain formation of spectral lines. (Repeated)

Numerical Topics: Energy transitions, Spectral wavelength calculation, Ionisation energy

Chapter 13 – Nuclei

1. Relation between mass defect and binding energy. (2025)

2. Characteristics of nuclear force. (2023)

3. Explain nuclear fission and fusion. (2024)

4. Radioactive decay law derivation. (Probable 2026)

5. Half-life explanation. (Repeated)

6. Binding energy curve explanation. (Probable 2026)

7. Explain alpha, beta, gamma decay. (Repeated)

8. Nuclear stability explanation. (Repeated)

Numerical Topics: Binding energy, Half-life calculations, Decay constant

Chapter 14 – Semiconductor Electronics

1. Distinguish intrinsic and extrinsic semiconductors. (2023)

2. Explain working of p-n junction diode. (2025)

3. Theory of half-wave rectifier. (2024)

4. Derive efficiency of full-wave rectifier. (Repeated)

5.diode working and applications. (Probable 2026)

6. Logic gates truth tables. (2025)

7. Diode as switch explanation. (Probable 2026)

8. Semiconductor energy band diagram. (Repeated)

Numerical Topics: Diode calculations, Semiconductor conductivity, Rectifier circuits